For buildings with hip roofs, it's much easier if the building is rectangular, so that it has some type of Ridge. (see the diagram) You can still do a hip on a square roof, but you end up with 4 triangular pieces which are more difficult to connect and keep 'square'.
I know you don't want to hear this, but it does take some basic Algebra and geometry to figure out the dimensions to make your templates.
The Width (W), Length (L), and Height (Ht) of the roof are givens, or at least you figure out what they need to be. The Ridge (R) length is simple enough to figure out. The only challenge is figuring out the length of the line H1. (It is the hypotenuse of a right triangle, drawn perpendicular to sides W and L) H1 is a line drawn perpendicular to either side of the W or the L for the end or side template. The equation for H1 is pretty simple and can be done with a standard calculator with the square and square root functions.
For line H2, you don't even need to calculate it. If you can accurately draw lines W, L, and H1, then you just connect the points A and B to form the line H2. (See the diagram)
**Note: If you cut the roof panels out of anything thinker than cardstock (I.E.: Foam board and etc.), then you may want to 'chamfer' the interior surfaces so that they fit snuggly together.
If you follow these simple rules, you'll get a pretty accurate hip roof, without all of the continual "trim to fit" that it seems a lot of you do.
See the modified hip roof of the building in the upper right of the photo.
This Anglo-Saxon/Viking era building is a variation on the hip roof I just explained.
Happy Roof Building!